Hi,
You will probably find that the cubes do not have any UV coordinates mapped to them, so the very first pixel of the material is repeated across the whole surface.
You need to UV unwrap them in blender before exporting.
You can also see the UV co-ordinates by changing the octane kernel to info channel kernel in texture co-ordinate mode. The UV space on the objects will be show as a colour gradient from black 0,0 to yellow 1,1 (green along one axis and red along the other). If all you see is black in this mode, then the UV's are missing.
Another option is to go into the materials and change the "projection" of the image textures.
"Mesh UV" is one of the texture projection options (how the textures are mapped to objects), there are others as well.
There is information about these in the standalone manual:
http://render.otoy.com/manuals/Standalo ... age_id=901